Fast Neutron Cross Sections in the 2S–1D Shell

Total neutron cross sections for six elements in the 2S–1D shell have been measured in the energy region 0.8–3.0 MeV using a new method. The experiment utilizes the fast neutron flux from a nuclear reactor with the neutron energies being determined by a measurement of their time of flight.From the present results the resonance parameters for aluminum have been determined and examined in the context of earlier low energy results for this element. The observed widths, which range to greater than 100 keV, are found to be consistent with compound nucleus formation when the reduced widths are compared with the corresponding low energy data. It is concluded that the observation of resonances with large widths is not sufficient to discount compound nucleus formation.